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Python with Randomness

When you flip a coin or roll a die, you can guess what the outcome will be but cannot be certain about it. The result is random.

In computer programming, generating a random value (number) is very useful in many applications. Take the educational app ExtraMath, for example, you can generate random numbers combined with arithmetic operators to test a student on basic math skills such as addition and multiplication.

In Python, we can generate random numbers using the random library by importing it first:

import random

To generate a random integer, we can call the random.randint() function:

import random
x = random.randint(1,9)
print(x)

6

Do it one more time:

x = random.randint(1,9)
print(x)

4

and chances are you will get different numbers.

In the above code, the randint() function takes two parameters 1 and 9, which define the range for the random number. The generated random number is limited to between 1 and 9. That is, the above code will generate any integer among [1,2,3,4,5,6,7,8,9].

Example: Addition Game

Now that we know how to generate a random number, let's attempt to create a math game about addition.

Here is the idea --

  1. generate two random integers from 1 to 9;
  2. store them in two variables x and y;
  3. calculate x+y and store the result in z (correct answer);
  4. ask the user for the answer with input and store it in the answer variable;
  5. finally, compare the correct answer in z vs. that from the user in answer.

Try the following code:

import random

# Generate two numbers x and y
x = random.randint(1, 9)
y = random.randint(1, 9)
# Save the result of addition to z
z = x + y

# Show the numbers to the user
print(x, "+", y)

# And ask the user for an answer
answer = input("= ")

# Feedback to the user about correctness
if int(answer) == z:
  print("You are right!")
else:
  print("Wrong! The correct answer is", z)

4 + 2
= 6
You are right!

Run the code and test the program.

Run it again, and see what happens -- what is different now? What is still the same?